This project is to conduct, under NSF's Small Grants for Exploratory Research (SGER) Program, a site response study as a part of efforts to develop seismic site-response parameters for possible inclusion into the future National Earthquake Hazards Reduction Program (NEHRP) seismic provisions. Strong-motion data recorded in the western United States between 1922 and 1989 (including the data from the 17 October Loma Prieta earthquake) will be compiled. In a parallel effort, geologic and geotechnical data will be collected for the recording stations wherethe data exist in sufficient quantity to adequately define the sites. Based on an initial qualitative assessment of the strong-motion and geotechnical-site data, a preliminary site-classification scheme will be proposed and all data within each site class will be analyzed separately. The dependence of the data within each site category on other important factors, such as magnitude, distance, and the size of the recording station will be investigated. Attention will be focused on the data, through statistical analyses from the potentially more destructive large magnitude earthquakes and short epicentral distances. This study will update with newly record ground-motion data the current NEHRP provisions which are based on site-dependent response spectra developed almost 20 years ago. This project is jointly supported by NSF and the Nuclear Regulatory Commission (NRC) through an interagency agreement.
